Over the past few decades, there has developed a growing gap between the surging power consumption of consumer electronic devices and the power which can be supplied by on-board batteries. Additionally, frequent battery replacement is not an option for some situations, such as wireless sensor networks with thousands of physically embedded nodes. Micro-Electro Mechanical Systems (MEMS) energy harvesting is an emerging alternative for scavenging energy from natural sources, which is essentially inexhaustible, such as mechanical vibration, solar energy, thermal energy, etc. This essentially free energy source is available maintenance-free throughout the lifetime of the application. Many systems, such as wireless sensor networks, portable electronics and cell phones, could use this technology as a power source through some types of MEMS devices, such as electro-magnetic MEMS, electrostatic MEMS, and piezoelectric MEMS.
The currently available MEMS energy harvesting techniques in the market like photovoltaic cells and wind power harvesting have several technical barriers that need to be resolved, including low efficiency, scaling issues, limitations in the fundamentals of physics, and high cost. In solar cells, energy losses come from optical loss due to the shadow of the aluminum electrode grid and reflection from the solar cell surface, quantum efficiency, and internal resistance due to the resistivity of electrode. All prevent solar cell's efficiency from reaching greater than 20%.